The invention relates to buildings which include at least one thermal bridge break between a wall and an approximately horizontal concrete slab.
In general, a wall may separate a warm environment from a colder environment, for example the inside of a building from the outside.
In most cases, it is desired to provide insulation between these two environments, especially to limit the heat losses to the outside from a heated unit, to keep, on the other hand, the inside of a unit at a cool or moderate temperature when it is hot on the outside and/or to improve the thermal comfort of a construction intended for housing people.
A wall may also have the function of supporting approximately horizontal concrete slabs which are joined to it and which, for example, may form part of the construction of a floor. These slabs may rest on the ground. Very often they extend at a certain height above the ground, for example in the case of a lower storey. The joint between the wall and the slab is therefore intended to provide the slab with support on the wall side and to anchor it into the wall.
When this joint is provided by the concrete of the wall and/or the slab, and by the rebars contained in the concrete of the wall and/or the slab, a thermal bridge is created which helps to conduct heat between the end of the slab in contact with the wall and the wall itself. Such a joint forms a more marked thermal bridge when the faces of the wall on the slab side have been coated with an insulating material.
To limit heat exchange between the wall and the slab, it is known to provide thermal bridge breaks located at the junction between the wall and the slab by interposing a thickness of insulation between the inner face of the wall and the end of the slab. The mechanical joint between the slab and the wall is itself formed by means of a rebar which is run both into the concrete of the wall and into that of the slab and which passes through the thickness of insulation.
This rebar has a high thermal conductivity. Each reinforcement which constitutes it and which passes through the thickness of insulation from the slab and towards the wall, or vice versa, constitutes per se an elementary thermal bridge. The amount of rebars providing the mechanical joint can result in a not insignificant heat flux.
From a thermal standpoint, such an arrangement, although constituting an improvement over structures which were described above and which do not have any thermal bridge break device, is worthy of being further improved.
The object of the invention is therefore to increase the thermal performance of such a thermal bridge break, while maintaining the required mechanical properties of the joint between the wall and the slab, which slabs may in some cases extend approximately horizontally above a void.
For this purpose, the invention provides an elementary module intended to form a thermal bridge break between a wall and an approximately horizontal concrete slab, characterized in that it comprises:
at least one beam made of a composite, intended to form a member for joining the slab to the wall and having a reduced ability to conduct heat; and
a longitudinal element made of an insulating material, which is intended to be interposed between the slab and the wall and right through which at least one channel for housing the beam passes.
According to other features of this elementary module:
the beam is made in the form of a section made of a polymer reinforced with a network of glass fibres and treated in order to be fireproof;
one portion of the beam, located at one end of the beam and intended to be embedded in the slab, includes additional means for fastening to the slab;
the additional fastening means comprise cramps;
the additional fastening means comprise means for joining to a rebar in the slab;
the section of the beam defines holes which extend along its length and are each intended to firmly house an iron bar forming a means of joining to the rebars of the slab;
the beam is made in the form of a section;
the beam includes a coating capable of withstanding hydrolysis;
the coating is made of a resin;
the beam is made of a high-performance concrete reinforced with polyethylene fibres;
the beam has the overall shape of a section with a cross-section substantially in the form of a T;
the cross-section of the beam has a bulge lying substantially at the free end of the base of the T; and
the beam has a cross-section xe2x80x9cin the form of a railway railxe2x80x9d.
The subject of the invention is also a building structure comprising:
at least one wall;
at least one approximately horizontal concrete slab; and
at least one thermal bridge break having a thickness of insulation interposed at the junction of the wall with the slab between a face of the wall and a corresponding end of the slab, characterized in that the thermal bridge break comprises a plurality of beams, distributed uniformly along the junction, each of the beams having, at a first end, a first portion rigidly secured to the wall, at a second end, a second portion embedded in the concrete of the slab and a third portion intermediate between the first portion and the second portion and passing through the thickness of insulation, the plurality of beams supporting the slab on the wall side and anchoring it into the wall.
According to further features of this building structure:
the thermal bridge break is formed by a plurality of elementary modules as defined above, which are juxtaposed along the length of the junction between the wall and the slab;
the base and the flanges of the T which substantially define the cross-section of the beam are oriented in approximately vertical and approximately horizontal directions, respectively;
the base of the T which substantially defines the cross-section of the beam faces approximately upwards and the flanges of the T are below this base.
The beams allow the thermal performance of the thermal bridge break to be improved.
In the first place, the use of beams makes it possible to use materials, particularly composites, whose thermal conductivity is very much lower than that of iron.
In addition, the use of beams makes it possible to reduce the amount of material involved in the construction of the mechanical joint, and therefore the propagation of heat by and the degradation in thermal performance of the thermal bridge break.
Firstly, a beam has, for an equivalent amount of material, mechanical properties for joining and supporting the slab which are superior to those obtained with rebars.
Secondly, the beams are intended to be placed uniformly along the length of the junction, leaving an approximately constant space between each of them. The number of beams used per unit length of the junction is therefore well controlled.
Finally, the shape of the beams may be optimized so as to reduce their cross-section which also forms the heat flow area and which it is consequently desired to make as small as possible, while maintaining the required mechanical properties for providing the joint between the slab and the wall. By this means, the beams allow the thermal performance of the thermal bridge break to be further improved.